Melting on the surface of the Greenland Ice Sheet. @bberwyn photo.How will global warming affect the flow of the jet stream?

Staff Report

Scientists are tracking yet another global warming feedback mechanism that will have dire consequences for coastal communities around the world. Melting sea ice and overall rapid warming in the Arctic are factors in the development of so-called blocking high pressure systems — air masses spinning clockwise that block cold, dry Canadian air from reaching Greenland.

The highs tend to enhance the flow of warm, moist air over Greenland, contributing to increased extreme heat events and surface ice melting, according to the study. That circulation pattern leads to more melting of the Greenland Ice Sheet, according to new research published online in the Journal of Climate last month, co-authored by Jennifer Francis, one of the pioneers in studying how global warming is affecting the jet stream. Continue reading “Climate: Jet stream shifts may speed Greenland meltdown”→

Oceans warming under a thickening blanket of greenhouse gases are licking at the edge of Antarctica and carving new channels in the bottom of ice shelves all around the frozen continent, researchers said this week in a new study led by scientists with the National Snow and Ice Data Center.

Those channels, characterized as “upside-down rivers” by the scientists, may make the ice shelves more prone to collapsing, which could speed up the flow of ice and the increase the rate of sea-level rise. Overall, some Antarctic ice sheets have thinned by about 18 percent and the rate of melting is accelerating, other research shows.

After studying a new ice core sample from McMurdo Sound, researchers say they’re a bit closer to one of the holy grails of climate science — understanding how Antarctic ice sheets will respond to increasing concentrations of atmospheric carbon dioxide.

The scientists looked at a 3,735-foot sediment core to reconstruct the Antarctic ice sheets’ history in an effort to create a climate model that mirrors conditions during the Miocene Era, when atmospheric CO2 levels were slightly higher, at 500 parts per million, than the 400 ppm level reached just last year, and global average temperatures were about 3 to 4 degrees Celsius higher than today. Continue reading “Antarctic ice sheets may be more sensitive to CO2 than we thought”→

‘It is high time that this essential irreversibility is placed into the focus of policy-makers’

Staff Report

Today’s debates about global warming impacts are much too shortsighted, according to a new analysis, which warns that, at the current rate of greenhouse gas emissions, the Earth is likely to suffer irreparable damage that could last tens of thousands of years.

“Much of the carbon we are putting in the air from burning fossil fuels will stay there for thousands of years – and some of it will be there for more than 100,000 years,” said Oregon State University paleoclimatologist Peter Clark. “People need to understand that the effects of climate change on the planet won’t go away, at least not for thousands of generations,” said Clark, lead author of the article. Continue reading “Policy makers must take long-term view of climate change”→

How quickly will the West Antarctic Ice Sheet melt away under global warming? @bberwyn photo.

‘All signs suggest the ice from West Antarctica could disappear relatively quickly …’

Staff Report

An in-depth survey of Antarctica’s rugged Ellsworth Mountains suggests that the West Antarctic Ice Sheet could melt quickly under the influence of global warming, potentially raising global sea level by three meters.

A new study tracks the accelerating heat buildup in the world’s oceans.

New study finds deep-down warming

Staff Report

Heat trapped by greenhouse gases is building up in the oceans at an increasing rate, according to researchers who are trying to get a more detailed understanding of the oceans’ role in the global climate cycle.

After studying data from a variety of sources, the researchers with Lawrence Livermore National Laboratory andthe National Oceanic and Atmospheric Administration found that half of the global ocean heat content increase since 1865 has occurred over the past two decades. Continue reading “Climate: Ocean heat buildup is accelerating”→

Extreme melting on the surface of the Greenland ice sheet could change the sea level rise equation.

Study shows that 2012 melting created a dense ice cap

Staff Report

When warm temperatures in 2012 caused an extreme melting episode across much of the Greenland Ice Sheet, it may have fundamentally altered the way the near-surface snow layers absorb water, according to a new study published in Nature Climate Change.